What Is Interlock Fabric?
Interlock is a double-knit fabric that is smooth on both faces. Where single jersey has a flat front and a looped back, interlock has two flat fronts, because it is effectively two fine knits locked together as they are made.
You will see it called interlock knit fabric, cotton interlock, or double knit. The last is a category rather than a synonym — interlock is the most common double knit in apparel, but not the only one.
How interlock is made
It is knitted on two sets of needles working against each other, so two layers of loops are formed simultaneously and interlocked stitch by stitch. Structurally it is closest to two fine 1x1 ribs knitted into one another, which is where the name comes from.
That construction is also why it costs more. Roughly twice the knitting and more yarn per square metre go into it than into a single jersey of the same fibre, and the price reflects that before anyone has cut a pattern.
What the double construction buys you
- No curling. The tensions balance across the two faces, so a cut edge lies flat. This is the single most practical difference from single jersey, and it decides what a designer can do with a raw edge.
- Two usable faces. No right side to get wrong at the cutting table, and reversible garments become possible.
- Opacity. Two layers of loops hide what is underneath, which matters for white and pale garments and for anything fitted.
- Shape retention. It stretches less than jersey and holds its shape better through wear and washing.
- A smoother printing surface. Flat on both faces and stable under tension, which is why it is the usual base for sublimation and large-area prints.
Interlock vs jersey
| Interlock | Single jersey | |
|---|---|---|
| Faces | Smooth on both | Smooth front, looped back |
| Curls when cut | No | Yes, always |
| Weight | Heavier for the same yarn | Lighter |
| Stretch | Less, recovers better | More, recovers less |
| Opacity | High | Lower, can show through |
| Drape | More body, less fluid | Softer, drapes more |
| Cost per metre | Higher, twice the knitting | Lower |
| Suits | Polos, kidswear, structured tops, print bases | T-shirts, vests, summer dresses |
Where interlock is used
In cotton, it shows up wherever a knit needs more body than a t-shirt: polo shirts as an alternative to piqué, structured tops and dresses, and a great deal of children's clothing, where the stability survives repeated hot washing and the opacity matters to parents.
In polyester, interlock is the standard base for sports shirts and anything sublimated. Sublimation needs a flat, stable polyester surface to print into, and a fabric that curls at the edge or distorts under tension makes accurate placement impossible. If you are planning all-over printed garments, expect to be quoted poly interlock.
When it is not the right choice
Interlock is not a premium upgrade to jersey, and treating it as one produces disappointing garments. It costs more, weighs more per square metre and drapes less, so a t-shirt made in interlock feels stiff and boardy rather than luxurious, and it ships heavier. If the garment's job is to drape softly, jersey is not the cheaper compromise; it is the correct fabric.
What a factory needs from you
The weight in GSM, the composition, and what the fabric has to do — hold a shape, stay opaque, or carry a print. That last one is the useful answer, because it is what tells us whether interlock is right at all or whether you are describing a jersey or a piqué garment. A reference garment settles it fastest, as always.
We knit and sew interlock every week at our own floor in Narayanganj, from a 100-piece minimum per style. Tell us what the garment has to do and we will tell you honestly whether interlock earns its extra cost on that style, or whether it does not.
Frequently asked questions
What is the difference between interlock and jersey?
How many sets of needles knitted it, and everything follows from that. Single jersey is knitted on one set, giving a smooth face and a looped back, lighter weight, more stretch, and edges that curl when cut. Interlock is knitted on two sets so two layers interlock stitch by stitch, giving a fabric smooth on both faces that lies flat when cut, weighs more for the same yarn, stretches less, recovers better and hides what is underneath. Interlock costs more because it takes roughly twice the knitting. Neither is superior; they answer different briefs.
Does interlock fabric curl?
No, and that is its most practical advantage. Single jersey curls at a cut edge because its loops all pull toward one face and the tension has to go somewhere. Interlock forms two balanced layers, so the tensions cancel and a raw edge lies flat. For a designer this is the difference between being able to leave an edge raw or having to hem, bind or rib it, and it should be settled before the pattern is cut rather than discovered on the first sample.
Is interlock fabric good for t-shirts?
Usually not, and it is worth being clear about that because interlock is sometimes sold as an upgrade. It costs more, weighs more per square metre and drapes less than single jersey, so an interlock t-shirt tends to feel stiff and boardy rather than premium, and it ships heavier. Interlock earns its cost where a garment must hold its shape, stay opaque, or take a large flat print. If the job is to drape softly against the body, jersey is not the cheap compromise, it is the right fabric.
What is interlock fabric used for?
In cotton: polo shirts as an alternative to pique, structured tops and dresses, and a great deal of children's clothing, where the stability survives repeated hot washing and the opacity reassures parents. In polyester: sports shirts and anything sublimated, because sublimation needs a flat, stable polyester surface to print into and a fabric that curls or distorts under tension makes accurate placement impossible. If you are planning all-over prints, expect a poly interlock quote.
Is interlock the same as double knit?
Interlock is a double knit, but double knit is the wider category. Any fabric knitted on two sets of needles to produce two interconnected layers is a double knit, and interlock is the most common one in apparel. Others exist, including double pique and various rib-derived double constructions. In practice, when a garment factory quoting knitwear says double knit without further qualification, interlock is usually what is meant, but it is worth confirming rather than assuming, because the weights and the prices differ.
Is interlock fabric stretchy?
It stretches, but noticeably less than single jersey and much less than rib, and that is deliberate rather than a shortcoming. The interlocked double structure resists extension and pulls back firmly, which is exactly why it holds its shape through wear and washing where a jersey garment would grow. For fitted shapes that need real stretch, elastane is added to the blend. If you need the fabric itself to do the stretching, rib or a jersey with elastane will serve better.
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